1. Field of the Invention
The present invention relates to a method for allocating an Internet protocol (IP) address to a mobile station in a mobile communication system; and, more particularly, to an IP address allocating method which can quickly allocate an IP address and improve efficiency of radio resources application by simplifying an address allocating procedure by cooperating with a session management protocol procedure and dynamically allocating the IP address to the mobile station in an IP based-mobile communication system.
This work was supported by the IT R&D program for MIC/IITA. [2005-S-404-22, “Research and development on 3G long-term evolution access system”].
2. Description of Related Art
Currently, a standard on a passive Internet Protocol Version 6 (IPv6) address allocating method and a dynamic IPv6 address allocating method is described as a method for allocating an IPv6 address to a mobile station in a 3rd Generation Partnership Project (3GPP) Release 6. The passive address allocating method is a method for allocating an IPv6 prefix by a provider in subscribing a mobile station. The dynamic address allocating method is a method for allocating an IPv6 address to the mobile station in a packet data protocol (PDP) activation procedure, i.e., a session management procedure. Stateless address auto-configuration and stateful address auto-configuration methods are suggested in the 3GPP in order to allocate a dynamic IPv6 address of the method described above.
When IPv6 address auto-configuration is applied, a signal procedure performed by an internet service provider (ISP) is divided into two steps. A first step is a signal procedure using a control plane of a mobile communication system. A second step is a signal procedure using a user plane. The signal procedure of the first step means a PDP context activation procedure by a session management protocol. The signal procedure of the second step is a signal procedure by an Internet protocol such as Internet control message protocol (ICMP). As described above, the signal procedure by the Internet protocol may be divided into the stateless auto-configuration procedure and the stateful auto-configuration procedure.
The stateless auto-configuration procedure is a method for allocating the IPv6 address through cooperation between a mobile station and a gateway of a core network, e.g., a gateway General Packet Radio Service (GPRS) support node (GGSN) in 3GPP. In the stateless auto-configuration procedure, when a prefix part of the IPv6 address is transferred to the mobile station, the mobile station configures an IPv6 address by combining the received prefix part and the interface identification (interface-ID). In comparison, the stateful auto-configuration procedure is an IPv6 address allocating method through cooperation among a mobile station, a gateway of a core network, and a dynamic host configuration protocol (DHCP) server of an Internet service provider (ISP). The current 3GPP adopts the stateless auto-configuration method as a mandatory method and the stateful auto-configuration method as an optional method.
FIGS. 1 and 2 are diagrams illustrating an IPv6 address auto-configuration procedure suggested in a conventional 3GPP standard. FIGS. 1 and 2 show the IPv6 address auto-configuration procedure through a signaling procedure performed among a mobile station (MS) including a terminal equipment (TE) and an equipment (UE), a serving GPRS support node (SGSN)/gateway GPRS support node (GGSN) existing on a core network, and an Internet service provider (ISP). Each of FIGS. 1 and 2 will be described hereinafter.
FIG. 1 is a flowchart describing the stateless address auto-configuration method in the conventional mobile communication system, e.g., 3GPP.
A mobile station 10 accessing to a mobile communication network transfers an “Activate PDP Context Request” message to an SGSN 11 to dynamically receive an IPv6 address as one of a session management (SM) protocol procedure at step S101.
The “Activate PDP Context Request” message is a message for activating a PDP context and configuring a service session between the mobile station and the core network. The “Activate PDP Context Request” message includes parameters such as Access Point Name (APN), Quality of Service (QoS), Network Service Access Point Identifier (NSAPI), an Internet Protocol (IP) address and cooperation protocol, and a Protocol Configuration Option (PCO) for a service (see FIG. 6A).
In particular, when it is requested to allocate a dynamic IPv6 address, the mobile station 10 configures a PDP address IE of the message as “0” and transfers the PDP address IE to the SGSN 11. The SGSN 11 receiving the message creates and transfers a “Create PDP Context Request” message to a GGSN 12 at step S102.
The GGSN 12 receiving the “Create PDP Context Request” message divides the IPv6 address allocating method as a stateless address allocating method and a stateful address allocating method, cooperates with a Remote Authentication Dial-In User Service (RADIUS) server, which is an authentication server provided by the ISP, and allocates a prefix and an interface-ID using a prefix pool of the GGSN 12 at step S103. The interface-ID created in the GGSN 12 should be different from the interface-ID of the mobile station. The prefixes allocated to each mobile station should be differently allocated. The prefix allocated to the mobile station is created by the GGSN 12 through cooperation with external authentication server, i.e., an Authentication, Authorization, and Accounting (AAA) server.
The GGSN 12 performing the procedure creates a “Create PDP Context Response” message including an IPv6 address formed of a prefix and an interface-ID and transfers the “Create PDP Context Response” message to the SGSN 11 at step S104. The SGSN 11 receiving the “Create PDP Context Response” message stores the IPv6 address and transfers the “Activate PDP Context Accept” message (see FIG. 6B) to the mobile station 10 at step S105.
The mobile station 10 receiving the “Activate PDP Context Accept” message recognizes that a signal procedure of a control plane is completed, extracts the interface-ID from the received “Activate PDP Context Accept” message, and performs an IPv6 address auto-configuration procedure using the interface-ID extracted from the user plane or the interface-ID created by the mobile station 10.
The signal procedure of the user plane, i.e., an IPv6 address auto-configuration procedure, will be described in detail hereinafter. The mobile station 10 configures a link local address based on the interface-ID transmitted from the GGSN 12 or the interface-ID created by the mobile station 10, and transfers a “Router Solicitation” message (see FIG. 7A) to the GGSN 12 performing a router function at step S106.
The GGSN 12 periodically transfers a “Router Advertisement” message to the mobile station 10 corresponding to a response message with respect to the “Router Solicitation” message at step S107. In the “Router Advertisement” message, an M-flag and an L-flag are configured as “0” in order to notify that the procedure is the stateless auto-configuration procedure, and the prefix, the lifetime and the A-flag are included (Refer to FIG. 7B).
The mobile station 10 receiving the “Router Advertisement” message creates a global IPv6 address based on the interface-ID received through the step S105 or the interface-ID created by the mobile station 10, and the prefix received through the step S107.
FIG. 2 is a flowchart describing a stateful IPv6 address allocating method in a conventional mobile communication system such as the 3GPP.
The mobile station 20 accessing to a mobile communication network transfers the “Activate PDP Context Request” message to an SGSN 21 as a session management (SM) protocol procedure in order to dynamically receive an IPv6 address at step S201. The “Activate PDP Context Request” message is a message for activating a PDP context and configuring a service session between the mobile station and the core network. The “Activate PDP Context Request” message includes parameters such as Access Point Name (APN), Quality of Service (QoS), NSAPI, an IP address and cooperation protocol, and Protocol Configuration Option (PCO) for a service.
In particular, when the mobile station 20 requests dynamic IPv6 address allocation, a PDIP address IE of the message is configured as “0” and transferred to the SGSN 21. The SGSN 21 receiving the message creates and transfers the “Create PDP Context Request” message to a GGSN 22 at step S202.
The GGSN 22 receiving the “Create PDP Context Request” message recognizes the IPv6 address allocating method as a stateless address allocating method and a stateful address allocating method, and cooperates with the RADIUS server, which is an authentication server provided by the ISP. Also, the GGSN 22 allocates the prefix and the interface-ID through own prefix pool or through cooperation with own DHCP server at step S203. The interface-ID created in the GGSN 22 should be different from the interface-ID of the mobile station (MS) and a link local prefix such as FE80::/64 is used as a prefix.
The GGSN 22 performing the above procedure creates a “Create PDP Context Response” message including the IPv6 address formed of the prefix and the interface-ID, and transfers the “Create PDP Context Response” message to the SGSN 21 at step 204. The SGSN 21 receiving the message stores the IPv6 address and transfers the “Activate PDP Context Accept” message to the mobile station 20 at step S205.
The mobile station 20 receiving the “Activate PDP Context Accept” message recognizes that a signal procedure of a control plane is completed, extracts the interface-ID from the received “Activate PDP Context Accept” message, and performs an IPv6 auto configuration procedure based on the interface-ID extracted from the user plane or the interface-ID created by the mobile station 20.
The signal procedure of the user plane, i.e., the IPv6 auto configuration procedure will be described in detail as follows. The mobile station 20 configures a link local address based on the interface-ID received from the GGSN 22 and transfers the “Router Solicitation” message to the GGSN 22 performing a router function at step S206.
The GGSN 22 periodically transfers a “Router Advertisement” message to the mobile station 20 corresponding to the response message with respect to the “Router Solicitation” message at step S207. In the “Router Advertisement” message, the M-flag is configured as “1” in order to notify that the procedure is the stateful address auto-configuration procedure, but the prefix is not included differently from the case of FIG. 1.
The mobile station 20 receiving the “Router Advertisement” message receives a stateful IPv6 address by performing a Dynamic Host Configuration Protocol (DHCPv6) procedure following RFC 3315 through cooperation with the DHCP server of the ISP at step S220.
When the DHCPv6 procedure is performed, the GGSN 22 transmits/receives a message by performing a DHCP relay function between the mobile station and a DHCP server. In the DHCPv6 procedure, the mobile station 20 transfers a “Solicit” message to the GGSN 22 in order to find a DHCP server at step S221. The GGSN 22 receiving the “Solicit” message transfers a “Relay-Forward” message to the DHCP server at step S222.
When the DHCP server receiving the “Relay-Forward” message transfers a “Reply” message including an IP address of the DHCP server to the GGSN 22 as a response message with respect to the message at step S223, the GGSN 22 transfers the “Advertisement” message included in the “Relay” message to the mobile station 20 at step S224.
The mobile station 20 receiving the “Advertisement” message selects the DHCP server and transfers a “Request” message to the GGSN 22 in order to request an IP address at step S225. The GGSN 22 receiving the message transfers a “Relay-Forward” message to the DHCP server at step S226.
The DHCP server receiving the “Relay-Forward” message transfers a “Relay-Reply” message including the IP address of the requested mobile station to the GGSN 22 at step S227. The GGSN 22 receiving the message transfers a “Reply” message to the mobile station 20 at step S228.
The GGSN 22 transfers the “Reply” message to the mobile station 20 at step S228 and performs a PDP modification procedure to configure a certified IPv6Aaddress for the mobile station 20. The above procedure will be described in detail as follows.
When the GGSN 22 transfers an “Update PDP Context Request” message to the SGSN 21 at step S208. The SGSN 21 receiving the “Update PDP Context Request” message transfers a “Modify PDP Context Request” message to the mobile station 20 at step S209.
The mobile station 20 transfers a “Modify PDP Context Accept” message to the SGSN 21 as a response to the “Modify PDP Context Request” message at step S210. The SGSN 21 receiving the “Modify PDP Context Accept” message transfers an “Update PDP Context Response” message to the GGSN 22 at step S211. Accordingly, the PDP modification procedure ends and a stateful IPv6 address allocation procedure of the mobile station ends.
In the conventional mobile communication system, an IPv6 address allocating procedure is performed to allocate an IPv6 address through a configuration procedure of a control plane by signaling and through cooperation between a plurality of function nodes, e.g., GGSN/SGSN, on the mobile station and the core network, and a signaling procedure of an IPv6 based user plane.
In the IPv6 address allocating method through the conventional two-steps message exchanging procedure, many delays may occur in initial IP configuration of the mobile station due to a complex signal exchange procedure. Also, there is a problem that flexibility of the service is not secured in case that handover on the mobile station is performed to a region included in another domain.
When a plurality of signal procedures such as the conventional IPv6 address allocating method are performed, resource efficiency is low in a mobile communication system using limited radio resources. Also, the mobile communication system is not proper to a target of minimizing the delay of the control plane in the currently standardized 3GPP Evolution system.